In the interest of durability enhancement, ceramic heaters for heating an object to be heated generally employ a structure in which a heat-generating resistor formed of a high-melting-point metal such as tungsten is disposed in a pattern within a ceramic sintered body composed predominantly of alumina (refer to Patent Literature 1, for example).
The heat-generating resistor, which is formed in a linear shape or a plate-like shape, generates Joule heat by the passage of electric current therethrough. The heat generated in the heat-generating resistor is transmitted through the ceramic sintered body for raising the surface temperature of the ceramic sintered body.
A ceramic heater is required to have the capability of adjusting the surface temperature of a ceramic sintered body to a predetermined temperature. For example, the surface temperature of a ceramic sintered body can be controlled by varying the value of electric current which is passed through the heat-generating resistor. As the electric current value is increased, the amount of heat generated is increased correspondingly with a consequent rise in surface temperature, and, on the other hand, as the electric current value is decreased, the amount of heat generated is decreased correspondingly with a consequent drop in surface temperature.